1. Field of the Invention
This invention relates to a measuring device and more particularly to a device for obtaining a volume related measurement, such as the dimensional weight or the volume, of an article, such as a parcel.
The dimensional weight of an article is a notional weight of the article calculated at least to some extent in accordance with the dimensions of the article and more particularly but not necessarily exclusively calculated from the dimensions of the article assuming that the article is of uniform predetermined density.
2. Description of the Prior Art
Airline freight forwarding businesses generally bill customers in accordance with the weight of a parcel. Airlines, on the other hand, tend to bill the freight forwarding businesses in accordance with the space occupied. Thus, the airline freight forwarding businesses can make a loss on parcels containing low density articles. Some airline freight forwarding businesses first weigh a parcel and then take a subjective view as to whether the parcel is large for its weight. If it is, the parcel is then measured using a tape measure and the dimensional weight is calculated for costing purposes. This is a labour intensive exercise and because any decision to measure the dimensions of a parcel is based on the subjective view of an operator, errors inevitably occur.
In any event, it is always necessary to input dimensions of articles and the present invention relates to measuring devices which are capable of determining the external dimensions of articles. Suitable measuring devices have already been disclosed in for example patent specification W085/05175 in which magnetic and optical pulses are used to provide distance signals. A linear measuring device is also disclosed in U.S. Pat. No. 4760647.
The distances are determined by passing a measuring device over a surface and measuring the rotational movement of a roller mounted to the device and exposed to contact the surface. The roller must be made of gripping material so that it does not slip and as such inherently tends to wear and so that calibration of the device can become inaccurate. Presently replacement of the rollers leads to extended out-of-use time and requires skilled labour.